The present invention relates to a new packaging containing an alcoholic or nonalcoholic aqueous beverage based on anethole.
It also relates to a process intended to limit the loss of anethole present in an optionally alcoholic solution in contact with the wall of a packaging made of polymer material and to the use of a polymer film for the production of a packaging in contact with optionally alcoholic anethole solutions in order to limit the loss of anethole in contact with the wall of the packaging.
Aniseed-flavored beverages contain anethole or para-propenylmethoxybenzene, predominantly in trans form (higher than 96-97%). Anethole has the special property of being very poorly soluble in water (&lt;50 mg/l) and soluble in alcohol. In the presence of water anethole becomes cloudy, whereas in a water/alcohol solution of high alcohol content (of the order of 45% by volume) anethole remains in the dissolved state.
In the case of alcohol-free or weakly alcoholic beverages (4-9 vol %) an emulsifier is resorted to because anethole is no longer soluble.
When aniseed-favored beverages are stored, considerable degradation appears in the course of time, especially under the effect of:
light (cis-trans isomerization), PA1 oxidation in the presence of light, PA1 interaction between anethole and the packaging material. PA1 multilayer plastic bottles of the PP/B/PA and PET/B/PA type.
While it has been possible to overcome the abovementioned first two disadvantages with the aid of packages which are opaque to the ultraviolet and which act as a barrier to gases, this is not so with regard to the third point relating to the loss of anethole in contact with the packaging material.
In fact, in the case of the conventionally employed packaging made of polymer (polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate) a very large loss of flavor (up to 100%) is observed in the course of time in contact with the polymer walls, and this prevents aniseed-flavored beverages from being marketed in plastic packaging.
This problem is still more sensitive in the case of alcohol-free or weakly alcoholic beverages based on anethole, in the case of which the loss in contact with polymer is still more rapid.
A number of scientific observations illustrate the particular behavior of this compound:
Anethole has a low coefficient of solubility in water but a high coefficient of solubility in polymers. This phenomenon is all the more important in the case of beverages containing little or no alcohol. This induces a considerable electrostatic interaction with the surface of the polymer and the adsorption of anethole onto the latter.
Furthermore, the affinity of anethole for polymers is such that an absorption phenomenon takes place, due to insertion of this compound between the polymer chains. It therefore involves a dynamic adsorption/absorption phenomenon.
In addition, anethole exhibits a high tendency to polymerize to polyanethole. This polymerization of a cationic type is promoted by the highly nucleophilic nature of the methoxy group. This phenomenon takes place especially in the case of polymers derived from styrene, maleic anhydride or acrylonitrile, which are commonly employed as packaging for beverages. This is due to the fact that anethole reacts with the molecular chains of these polymers.
However, anethole can also react with the residual monomers, given the well-known reaction of copolymerization with styrene (T. Higashimura et al., Journal of Polymer Science: part A.1, vol. 10, 85-93 (1972)) or the terpolymerization with maleic anhydride and acrylic monomers such as acrylonitrile (T. Kobuko et al., Macromolecules, vol. 3, No. 5, September-October 1970, 518-523).
For all these reasons, at the present time no plastic packaging for anethole-based beverages is known.
A bottle made of a crushable aromatic polyamide has indeed been described in the Derwent abstract AN-92319511(39), but this document merely indicates that the bottle may contain beer, sparkling beverages or juices. This bottle is furthermore taken to be similar to PET bottles which, as is known, are unusable in the case of anethole-based beverages.
This is why at the present time aniseed-flavored beverages are packaged in glass bottles.
It is therefore desirable to propose new packaging made of polymer material enabling the inertness performance of glass to be attained or approached.